CHAPTER 12: BLOOD VESSELS AND CIRCULATION (copy)

FUNCTIONS OF THE CIRCULATORY SYSTEM

FUNCTIONS OF THE CIRCULATORY SYSTEM

1. Carries blood.

2. Exchanges nutrients, waste products, and gases with tissues.

3. Transports substances.

4. Helps regulate blood pressure.

5. Directs blood flow to the tissues.

Blood vessels outside the heart are divided into

pulmonary vessels systemic vessels

GENERAL FEATURES OF BLOOD VESSEL STRUCTURE

• Arteries • Arterioles • Veins • Venules • Capillaries

Tunics:

• tunica intima • tunica media • tunica adventitia

Elastic arteries

-the largest-diameter arteries and have the thickest walls -greater proportion of their walls is composed of elastic tissue, and a smaller proportion is smooth muscle -examples: aorta and pulmonary trunk

Muscular arteries

• include medium-sized and small arteries

• walls are relatively thick compared to their diameter

• most of the wall’s thickness results from smooth muscle cells of the tunica media

• frequently called distributing arteries

Arterioles

• transport blood from small arteries to capillaries

• smallest arteries in which the three tunics can be identified

Capillaries

• branch of to form networks • regulated by smooth muscle cells called precapillary sphincters • capillary walls consist of endothelium, which is a layer of simple squamous epithelium

Veins

Venules Small veinsMedium-sized veins Large veins

valves

ensure that blood flows toward the heart but not in the opposite direction

BLOOD VESSELS OF THE PULMONARY CIRCULATION

pulmonary trunk pulmonary arteries pulmonary veins(four; two from each lung)

Varicose veins

result when the veins of the lower limbs become so dilated that the cusps of the valves no longer overlap to prevent the backflow of blood

Thromboses

occurs when blood clots block veins

Phlebitis

inflammation of veins

Gangrene

death of body tissue due to a lack of blood flow or a serious bacterial infection

Aorta

largest artery; originates from the left ventricle

Divisions of aorta:

• Ascending aorta • Aortic arch • Descending aorta o Thoracic aorta o Abdominal aorta

Brachiocephalic artery

1st branch from aortic arch

Right common carotid artery

medial branch of the brachiocephalic artery; transports blood to the right side of the head and neck

Right subclavian artery

lateral branch of the brachiocephalic artery; transports blood to the right upper limb

Left common carotid artery

2nd branch of aortic arch; transports blood to the left side of the head and neck

Left subclavian artery

3rd branch of aortic arch;transports blood to the left upper limb

Internal and External Carotid Artery

branches of common carotid artery

Internal carotid artery

enter the brain to become circle of Willis

Circle of Willis

circular system of arteries around the brain’s base which keeps the brain oxygenated

Arteries of the Upper Limb

• Axillary artery • Brachial artery • Ulnar artery • Radial artery

Thoracic aorta

o Visceral arteries o Parietal arteries

Intercostal artery

provide blood to the intercostal muscles

Phrenic artery

provide blood to the diaphragm

Abdominal Aorta and Its Branches

• Visceral arteries Unpaired: o Celiac artery o Superior mesenteric artery o Inferior mesenteric artery Paired: o Renal artery o Suprarenal artery o Gonadal artery • Parietal arteries o inferior phrenic arteries o lumbar arteries o median sacral artery -

Arteries of the Pelvis

• Common iliac o Internal iliac o External iliac

Femoral artery

from external iliac and supplies the thigh

Popliteal artery

from femoral and supplies the posterior knee

Anterior and posterior tibial artery

from femoral and supplies shin area

Dorsalis pedis artery

from the anterior tibial

Fibular artery

aka peroneal artery; from posterior tibial artery; supplies the lateral ed and foot

BLOOD VESSELS OF THE SYSTEMIC CIRCULATION: VEINS

Superior vena cava -returns blood from the head, neck, thorax, and upper limbs to the right atrium of the heart

Inferior vena cava -returns blood from the abdomen, pelvis, and lower limbs to the right atrium

Brachiocephalic vein

drains into the SVC

Subclavian vein

lateral branch which drains into the brachiocephalic

Internal jugular vein

medial branch which drains into the brachiocephalic

External jugular vein

external vein of the neck and is the lateral branch which drains into subclavian

Axillary vein

medial branch which drains into the subclavian

Brachial vein

superficial vein which drains into the axillary

Cephalic vein

lateral branch which drains into the subclavian

Basilic vein

becomes the axillary vein; major superficial veins

Median cubital vein

usually connects the cephalic vein or its tributaries with the basilic vein

Veins of the Thorax

• Azygos vein • Hemiazygos vein • Intercostal vein

Common iliac vein

2 branches that join together to become the IVC; receives blood from lower extremities and brings it back to IVC

External iliac vein

receives all the blood from lower extremities; drains blood into the common iliac

Femoral vein

major lateral branch into the external iliac

Great saphenous vein

major medial branch into the external iliac

Popliteal vein

drains the posterior knee and drains into the femoral

Small saphenous

lateral branch draining to the popliteal

Anterior/Posterior Tibial

draining to the popliteal

pulmonary vessels

transport blood from the right ventricle of the heart through the lungs and back to the left atrium

systemic vessels

transport blood from the left ventricle of the heart through all parts of the body and back to the right atrium

Arteries

blood vessels that conduct blood away from the heart; usually carry oxygenated blood

Arterioles

small artery that leads to a capillary

Veins

blood vessels that brings blood back to the heart; usually carry deoxygenated blood

Venules

small vein that leads to a capillary

Capillaries

small network of vessels where air exchange happens

tunica intima

innermost layer, consists of an endothelium composed of simple squamous epithelial cells

tunica media

middle layer, consists of smooth muscle cells arranged circularly around the blood vessel

tunica adventitia

composed of dense connective tissue adjacent to the tunica media; becomes loose connective tissue toward the outer portion

Venules

have a diameter slightly larger than that of capillaries

Small veins

o slightly larger in diameter than venules o all three tunics are present

Medium-sized veins

o collect blood from small veins and deliver it to large veins o have three thin but distinctive tunics

Large veins

also have three thin but distinctive tunics

pulmonary trunk

branches into right and left pulmonary arteries

pulmonary arteries

extend to the right and left lungs; carry deoxygenated blood to the pulmonary capillaries in the lungs

pulmonary veins

exit the lungs and carry oxygenated blood to the left atrium

Ascending aorta

from the left ventricles, it goes upward; where coronary arteries branch off

Aortic arch

bend of the aorta

Descending aorta

longest part of the aorta; extends through the thorax and abdomen to the upper margin of the pelvis

Thoracic aorta

portion of the aorta in the thorax

Abdominal aorta

part of the descending aorta within the abdomen

Axillary artery

continuation of the subclavian artery inferior to the clavicle

Brachial artery

continuation of the axillary artery in the upper arm

Ulnar artery

medial branch of the brachial artery

Radial artery

lateral branch of the brachial artery

Visceral arteries

supply the thoracic organs

Parietal arteries

supply the thoracic wall

Celiac artery

to the stomach, pancreas, liver

Superior mesenteric artery

small and proximal large intestine

Inferior mesenteric artery

distal large intestine

Renal artery

to the kidneys

Suprarenal artery

to the adrenals

Gonadal artery

testicular and ovarian

inferior phrenic arteries

supply the diaphragm

lumbar arteries

supply the lumbar vertebrae and back muscles

median sacral artery

median sacral artery

Common iliac

goes to the lower extremity

Internal iliac

medial branch of common iliac; provides blood to the pelvic organs

External iliac

lateral branch of common iliac; goes down to the lower limb

Azygos vein

only found on the left side of the body; unpaired branch which drains into the SVC

Hemiazygos vein

2 sets of multiple veins that empty into the azygos

Intercostal vein

drains into azygos (left) and hemiazygos (right)

Internal iliac vein

2 branches that join together to become the IVC; drains blood from the pelvic area and brings it back to IVC

Portal system

a system of blood vessels that begins and ends with capillary beds and has no pumping mechanism

Inferior mesenteric vein

empties into the splenic vein